The present invention relates to a dental caries-preventive composition which is contains an antibody obtained by the immunization of an animal with cells or cell components of Streptococcus mutans. More particularly, the present invention relates to a dental caries-preventive composition which keeps the antibody stable for a long period of time and hence permits the antibody to exhibit its effect with certainty over a long period of time, thereby inhibiting the formation of dental plaque and preventing dental caries.
Dental plaque firmly adhering to the surface of teeth is composed of about 70% bacteria, about 20% polysaccharides produced by the bacteria and about 10% food remains. It is said that acids stored in dental plaque decalcify enamel, causing dental caries. Therefore, dental plaque is observed as a cause of dental caries.
Formation of dental plaque is accelerated due to the synthesis of polysaccharides from sucrose by oral bacteria, especially Streptococcus mutans. In more detail, Streptococcus mutans synthesizes adhesive polysaccharides such as dextran and mutan from sucrose through the production of GTF (glucosyltransferase, dextran-synthesizing enzyme). The thus synthesized polysaccharides incorporate Streptococcus mutans as well as other bacteria and viruses, forming dental plaque having a given bacterial bouquet. In addition, bacteria such as Streptococcus mutans produce acids by utilizing various kinds of sugar and the thus produced acids decalcify the surface of enamel by remaining in polysaccharides and bacterial walls.
Accordingly, it is desirable to decrease the number of Streptococcus mutans in the mouth and suppress the formation of dental plaque in order to prevent dental caries.
It is known in British Pat. No. 1,505,513 that colonization of Streptococcus mutans in the mouth is suppressed by using mother's milk obtained by immunizing a cow with whole bacterial bodies of Streptococcus mutans.
The present inventors studied antibodies which are amongst the antibodies to various antigens derived from Streptococcus mutans and inhibit the colonization of Streptococcus mutans in the mouth. As a result, the inventors found that antibodies contained in antiserum and milk obtained by immunizing mammals with Streptococcus mutans, its cell-wall fraction, fibrous substance fraction, pilus component fraction, glucosyltransferase fraction and protein antigen fraction have a dental-plaque-formation suppressing effect. However, these antibodies are not stable in a dental caries-preventive composition, and particularly they become readily deactivated in the presence of an anionic surface active agent such as sodium lauryl sulfate. Thus it is necessary to incorporate the antibody into a dental caries preventive composition in such a manner that it remains effective for a long period of time.